import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.StandardCharsets;
import java.util.Scanner;

public class TcpEchoServer {
    private ServerSocket serverSocket=null;
    public TcpEchoServer(int port) throws IOException {
        serverSocket=new ServerSocket(port);
    }

    public void start() throws IOException {
        System.out.println("启动服务器");
        while(true){
            Socket clientSocket=serverSocket.accept();
            processConnect(clientSocket);
        }
    }

    private void processConnect(Socket clientSocket) {
        System.out.printf("[%s,%d] 客户端上线!\n",clientSocket.getInetAddress(),clientSocket.getPort());
        try(InputStream inputStream=clientSocket.getInputStream();
            OutputStream outputStream=clientSocket.getOutputStream()) {
            Scanner scanner=new Scanner(inputStream);
            PrintWriter writer=new PrintWriter(outputStream);
            while(true){
                //1.读取请求并解析,可以使用read,也可以使用Scanner来辅助完成

                if(!scanner.hasNext()){
                    System.out.printf("客户端下线");
                    //连接断开
                    break;
                }
                String request=scanner.next();
                //2.根据请求计算响应
                String response=process(request);
                //3.返回响应到客户端
                //outputStream.write(response.getBytes());
                writer.println(response);
                //打印日志
                System.out.printf("[%s,%d] req:%s ,resp:%s\n",clientSocket.getInetAddress(),clientSocket.getPort(),
                        request,response);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        TcpEchoServer server=new TcpEchoServer(9090);
        server.start();
    }
}
